不同剂量氟对大鼠成骨细胞激活与BMP-4、BMP-2和Smad-4表达的影响

目的探讨过量氟对大鼠成骨细胞系BMP-2、BMP-4及其信号转导物Smad-4表达水平的影响及其与氟骨症发病机制的关系。方法利用饮水加入氟化钠(NaF)进行大鼠染氟实验,采用原位杂交技术、 Western blot技术、免疫组织化学方法,对氟中毒大鼠骨组织成骨细胞系进行BMP-4、Smad-4的mRNA水平和 BMP-2、BMP-4蛋白质水平的定量分析。结果 NaF可刺激慢性氟中毒大鼠椎骨各包被成骨细胞增殖,并诱导 BMP-2、BMP-4和Smad-4的表达。在低钙偏食组慢性氟中毒大鼠BMP-4、Smad-4 mRNA和BMP-2、BMP-4 蛋白质水平稍增高但与对照组相比差异无统计学意义(P>0．05);在高钙和低钙加氟组Smad-4 mRNA的表达均增高,与对照组相比差异有统计学意义(P<0．001);在低钙加氟组Smad-4 mRNA水平与BMP-4 mRNA水平和BMP-2、BMP-4蛋白质表达水平具有一定相关性(r=0．53)。结论过量氟可刺激大鼠成骨细胞系激活、增殖能力增强,但在增殖能力增强的成骨细胞中BMP-4 mRNA和BMP-2、BMP-4蛋白质水平表达无明显增高,可能与氟骨症的骨化不良有关;NaF刺激Smad-4 mRNA过表达可能与氟骨症骨相损害的信号转导途径激活有关。

The effect of different dosage of fluoride intake on activation of osteoblasts and the expression of BMP-2,BMP-4 and Smad-4

Objective To explore the effect of excessive fluoride on the expressions of BMP-2, BMP-4 and Smad-4 in rat osteoblasts and its correlation with pathogenic mechanism of flurosis. Mehtods Rat flurosis model was established by drinking diet water added with fluroride sodium (NaF), and the mRNA expressions of BMP-4 and Smad-4 and protein products of BMP-2 and BMP-4 in osteoblasts of rats with flurosis were analyzed quantitatively by hybridization in situ, Western blot and immunohistochemistry methods. Results NaF stimulated the proliferation of periosteal envelop osteoblast in rats with flurosis, and also induced the expression of BMP-2, BMP-4 and Smad-4. In the flurosis rats with low-calcium diet group,BMP-4 mRNA expression level and the protein production of BMP-2 and BMP-4 were only slightly increased without statistical significance compared with those of control group (P > 0.05); Smad-4 mRNA level both in low-calcium and high-calcium groups was elevated with significant difference compared with that in control group (P < 0.001) ;The expression of Smad-4 mRNA correlated with the expression of BMP-4 mRNA, the protein expression of BMP-2 and BMP-4 (r = 0.53). Conclusions Excessive fluoride stimulates the activation of rat osteoblast and increases its proliferation. However, the expression of BMP-4 mRNA and the expression level of BMP-2 and BMP-4 proteins are not obviously elevated in the highly proliferative osteoblasts, which is associated with the impaired ossification. The over-expression of Smad-4 mRNA stimulated by NaF may correlate with the activation of signaling transduction pathways in the skeletal lesion of chronic fluorosis.